Patent GB-1122118-A (GB)
Title: Improvements in or relating to release means for the compressed air brakes of locomotives
IPC: B60T15/18
Filed: 1966-12-02
Abstract: 1,122,118. Compressed-air brakes for rail vehicles. KNORR-BREMSE G.m.b.H. 2 Dec., 1966 [3 Dec., 1965], No. 54189/66. Heading F2F. Controlled partial release of the compressedair brakes of a locomotive is effected without affecting the remaining brakes of the train by a release means comprising a manually operated valve 28 in the driver's cab operating in association with a relay valve 6 which has a pair of control pistons 11, 19 secured to a common slidable exhaust tube 14, the upper end of which co-operates with an inlet/exhaust valve element 15 to control both exhaust port 17 and inlet port 7, such that in the upper position shown air is supplied from reservoir 3, via a control valve 2 controlled by the pressure in the brake pipe 1, to locomotive brake cylinders . 10 (or a relay valve for supplying same), while in the lower position of valve element 15 air is exhausted from the brake cylinders 10 via the interior 16 of the tube 14. The control piston 11 is acted on from above by brake cylinder pressure in chamber 8 and from below by pressure in inlet chamber 5 which communicates by way of a normally open electromagnet valve 23, the latter pressure being supplemented by a spring 11. Control piston 19 is acted on from below by atmospheric pressure and from above by the pressure in chamber 18 which is controlled by the manually operated valve 28. Valve 28 is spring-returned to a central position, in which chamber 18 is isolated except for a connection via non-return valve 22 to the chamber 12 which automatically vents chamber 18 when the train brakes are released. Movement of valve 28 in one direction feeds pressure from chamber 12 to chamber 18, overcoming the effect of spring 13 to cause closure of the inlet 7 and venting of the brake cylinder to an extent determined by the length of time valve 28 remains off-centre in this direction. Return of valve 28 to the central position causes the valve element 15 to lap, holding a reduced pressure in the brake cylinder, while movement of valve 28 in the opposite direction vents the chamber 18 so that inlet 7 is re-opened to restore full braking of the locomotive. The maximum amount of release possible is limited by the force exerted by spring 13. A non- return valve 30 is provided so that if brake pipe 1 is vented in conjunction with an emergency application of the train brakes the chamber 18 is vented directly to the train pipe. In order to ensure that air is not trapped in the brake cylinder when the train brakes are released, a non-return valve 20 is provided between the brake cylinder and the inlet chamber 5. The electromagnetic valve 23 is operated in conjunction with a second locomotive braking system (not shown) to disconnect chamber 12 from inlet chamber 5 and vent it to atmosphere in that event. -In a modification (Fig. 2, not shown), the manually operated valve 28 is supplied from brake pipe 1 instead of from the chamber 12. The operation of the modified system is unchanged excepting that, since the pressure in brake pipe 1 is higher than the corresponding pressure in chamber 12, it is possible to charge chamber 18 to a pressure sufficient to overcome spring 13 permanently and so completely release the locomotive brakes.